I don't mean to say that if you aren't wearing wool you are wearing a skirt.
I think we all have a line drawn in our mind and on one side of that line is kilts and on the other side is skirts.
That line is probably different for every person on this forum, but I think we all have a line somewhere and wouldn't wear what falls on the skirt side of our own line.
I don't really think there is any "real" line for where the division is for kilts and skirts. It's a personal decision we all have to make. I am certainly tempted by the poly/vicose kilts, if for no other reason, because they are a lot cheaper. However, I wouldn't feel comfortable in one.